Every lunchtime, Lisa, 14, eats her packed lunch before heading to the tuck shop of her school in Derbyshire. A gap leads to an enclave five metres behind the building, where she and about 15 others congregate to light up their lunchtime cigarette.

“There are two non-teaching members of staff who run the tuck shop and if they turned round properly they would catch us all,” she says. “We davidoff cigarette in an alleyway that joined our two playgrounds together but then they put up fake cameras, so no one does it there any more — and you can’t do it anywhere near the loos because there are smoke alarms that go off.”

Millions of pounds have been spent on persuading them to stop. So why do teenagers still smoke?

This “crafty fag” scenario has been played out in school grounds for decades. What sets Lisa’s generation apart is that they are blowing smoke in the face of the most ferocious antitobacco campaign to date, involving more warnings to young people than ever that the nasty weed can kill, cause wrinkles and seriously impinge on your social life.

Since the first government White Paper on smoking in 1998, the focus on pressurising young people not to smoke has been constant. The anti-smoking crusade has culminated in the present ban on tobacco advertising and smoking in public places, but it shows no sign of stopping there. Since the clampdown on smoking came into full force, the age at which a person can buy cigarettes legally has risen from 16 to 18, but it is hoped that a ban on sales of tobacco from vending machines, which is to be enforced next year, will make it even harder for youngsters to get hooked. Health messages are plastered on cigarette packs and picture warnings will appear on all tobacco products by October. Yet despite such steps and the millions spent on raising awareness that smoking can kill, over the past decade the rate of decline in the number of young people smoking has at best flattened out and at worst, in some areas, actually worsened.

Lisa says she started smoking because her friends did, and that she didn’t think twice about the risks. “I know it’s bad for you but I don’t plan to do it for ever,” she says. “I can’t see the problem with it at the moment. It’s my choice and nobody else’s.”

This view is echoed by young voices around the country. In Wimbledon, southwest London, 13-year-old Alexandra says that “most people have tried it by the time they get into Year 8”. Andrew, 15, from Glasgow, says that “crowds of 20 or more stand outside our school smoking and nobody takes any notice”.

An annual government survey of secondary-school children in England, begun in 1982, has shown only slight fluctuations in the number of 11 to 15-year-old smokers since then, the figure hovering around the initial 11 per cent mark. According to the latest figures, produced in 2008, 6 per cent of 11 to 15-year-olds regularly smoke about six cigarettes a day — slightly fewer than two years previously. But the number of 16 to 19-year-olds who smoke had risen to 26 per cent in that time, and there are areas of the country where the percentage of young smokers has risen dramatically.

In Scotland a third of young people aged 16-24 now smoke — a return to a level last seen a decade ago — while teenage girls in the North West are among those most likely to take up the habit. Overall, two thirds of UK smokers still start before they are 18, and in England one 15-year-old in seven admits smoking regularly.

How have things gone so wrong? Why, after such an almighty effort to persuade them otherwise, do young people still perceive smoking as “cool”? Surveys have long shown that children are more likely to smoke if one or both parents do, and that they are influenced strongly by the habits of siblings and peers. But beyond these obvious connections, are there other factors involved in encouraging children to smoke? This week the Hospital Club in Covent Garden is hosting an event that will examine how smoking has maintained its allure — an allure highlighted in research from Nottingham University last week that revealed the prevalence of smoking images in British-made films.

Dr Alisa Lyons, of the UK Centre for Tobacco Control Studies (UKCTCS), counted the number of “incidents of smoking” and smoking references in the 15 most popular films released in the UK between 1989 and 2008, including Bridget Jones’s Diary, with Renée Zellweger, and About a Boy, starring Hugh Grant. Tobacco products were prevalent in seven out of ten films, more than half of which were classified as suitable for children under 15. Almost all were deemed suitable for under-18s.

Dr Lyons and health bodies including the Liverpool Primary Care Trust say that unless there is an overhaul of the film classifications system in the UK, the presence of smoking on the big screen will continue to influence a generation of young viewers. “The more young people are exposed to smoking images, the more it normalises the behaviour to them,” Lyons says. “Seeing actors smoking makes it more glamorous — and if young people don’t directly see the adverse side of smoking, a positive image is cast in their minds.”

Dr Lyons suspects that similar “positive smoking” messages are being taken from television programmes, which she aims to examine in future research. She says that screen exposure is not solely to blame but compounds vulnerabilities in teenage minds.

“Often members of this age group want to be accepted, so, if their friends try smoking, so will they,” she says. “For some there is a rebellious element to it and they use smoking to state their independence.” Some people even have doubts about the merits of anti-smoking campaigns, suggesting that they do more harm than good in their attempts to steer young people away from nicotine.

Indeed, evidence that anti-smoking messages make young people more likely to light up has been mounting for the past eight years, with one group of researchers finding that “quit smoking” campaigns appear to stimulate a teenage rebellious streak, sparking an interest in smoking that may not previously have existed. In surveys of nearly 1,700 pupils at US high schools, Professor Hye-Jin Paek, of the University of Georgia, found that no-smoking campaigns were effective only when they managed to convince teenagers that their friends were influenced by them. “Anti-smoking ads have the greatest impact on smoking attitudes and behaviour when adolescents think that their peers are listening to those messages,” Paek said. “Perception is sometimes more powerful than actual behaviour. It matters how they think their friends are responding.”

A link has also been suggested between the sexual awakening of young people and their desire to smoke. It is known that children who have sex at a young age are more likely to smoke, and a study at University College London found that pre-teens who had a boyfriend or girlfriend at 11 or 12 were at least twice as likely as their non-dating peers to start smoking in the next five years.

“The sexual connection is difficult to study,” says Professor Anne McNeill, of the University of Nottingham’s school of community health sciences (and deputy director of the UKCTCS). “But it could be that because of their dating they have aspirations towards maturity and adulthood and are attempting to enhance their popular image.”

But what becomes of teenage smokers? Are they destined to become hooked, or is smoking a passing phase of youth? Professor McNeill says that all the signs point to childhood smoking resulting in a lifelong addiction. In her research she measured the inhalation of chemicals among children who smoked and found them to be taking in as many damaging substances with each breath as adult smokers.

“Because they are still developing, their neurobiology may be more susceptible to the nicotine than it would be if they first tried smoking when they were older,” she says. “In effect, their internal wiring is being finalised, then they bombard it with smoking.”

Nicotine is known to affect the brain’s reward centres, releasing chemicals that tell the body it is doing something enjoyable and creating the potential for addiction. Research by the Cancer Research UK health behaviour unit at University College London indicated that children who smoke just one cigarette are twice as likely to take up the habit later in life, even if they don’t smoke for several years.

Many of those who start in childhood will join the ranks of those who want to stop — currently seven out of ten UK smokers. Even so, one adult in four still smokes. Admittedly this is far fewer than the one in two who lit up in the 1950s, but it is still a staggering number when you think that most smokers now do so in the full and certain knowledge that it increases their risk of developing lung cancer and conditions such as emphysema, as well as making them more likely to suffer from other forms of cancer, heart disease, diabetes and stroke.

With four million adults dying worldwide each year from smoking-related diseases, tobacco is a product that kills 60 per cent of its customers.

“The real issue is that these health messages can fall on deaf ears with children,” says McNeill. “Young people live in the here and now. Thirty is a lifetime away and they can’t imagine being that old.”